1. Field of the Invention
The present invention relates to a color ink jet recording method which permits sharp and high density recording of a color image, and more particularly to a color ink jet recording method using color inks such as yellow, magenta and cyan as well as black ink.
The present invention is applicable to any apparatus which uses a recording medium such as paper, cloth, non-woven material or even an OHP sheet, and particular applicable apparatuses include office equipment such as a printer, a copying machine and a facsimile machine, and mass-produced equipment.
2. Related Background Art
The ink jet recording method has been used in the printer, copying machine and facsimile machine because of its easiness for compaction in size, and colorization.
When the ink jet recording is applied to a color recording apparatus, it is necessary to use a special sheet having an absorption layer to attain a high tonality color image free from ink blur. Recently, as the ink is improved, an apparatus which permits the printing on a plain paper has been put into practice. However, the print quality to the plain paper is still in an insufficient level. One of the greatest factors therefor is the compatibility of the ink blur between different colors and the black record quality (especially the black character record quality).
When a color image is to be printed on a plain paper by the ink jet recording method, an instant dry ink which has a fast penetration velocity to the plain paper is usually used. As a result, a high quality image without the ink blur between different colors is attained in a color image area but the density in a black image area is low and so-called feathering in which the ink blurs along fibers of the paper occurs in the black image area.
For example, where a black image is present on a background color image area, the above problems in the black image area is relatively not prominent and the quality is not significantly degraded, but where the black image area is present independently from the color image area, the quality is degraded. Further, where the black image includes characters, the characters lack sharpness and are not clear and the quality is extremely poor.
In order to attain the high quality image having a high density in the black image area and no feathering, it is necessary to implant relatively low penetration velocity ink to the plain paper in a certain amount. In this case, however, the ink blur of the black ink and the color ink occurs at the boundary of the black image area and the color image area and the quality is significantly degraded.
The problem relating to the ink blur may be solved to a certain extent by a so-called fine mode in which an image is formed in a plurality of runs of main scan but the problems of the black image quality is not essentially solved.